The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component that can be created using a fabrication process) has decreased.
To provide electrical connections between elements of a transistor on the IC (such as gate, source, and drain) and external devices, conductive contacts and vias are formed in the IC. During the formation of the contacts, oxidation of the surfaces of the contacts may occur. The oxidation results in an oxidation material formed on the contact surface, such as a metal oxide, that may degrade the performance of the IC. For example, contact resistance for one or more elements of the transistor may vary out of a desired range. Therefore, it is desirable to remove such oxidation material. However, it is difficult for traditional methods to sufficiently remove the oxidation material on the contact surfaces without damaging parts of the transistor. As a result, ICs fabricated with traditional methods may not have optimal performance.
Therefore, while existing methods of forming contacts for transistor devices have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect.